Variable condenser



June 7,1927. "$631536 E. B. LEWIS VARIABLE CONDENSER Filed June 17. 1925 12 E 15 munm INVENTQR Ear/e B. Law's hf- 9M A'ITORNEY Patented June 7, 1927.

UNITED STATES EABLE BARNES LEWIS, OF WATER'BURY; CONNECTICUT,

VARIABLE CONDENSER.

Application filed June 17, 1925; Serial No. 37,700.

This invention relates to variable condens ers for use .in radio apparatus, and more particularly to a plate condenser having improved means for reducing the electrical leakage to the minimum.

A further object is to provide a condenser having stationary and movable plates, said stationary plates being mounted in a plurality of posts which are insulated from their supporting frames by means of insulating balls. I

A further object is to provide a device of the above nature which will be simple in construction, inexpensive to manufacture, easy to manipulate, compact, ornamental in appearance, and very eflicient and durable in use.

'With these and other objects in view, there has been illustrated on the accompanying drawings, one form in which the invention may be conveniently embodied in practice.

.Fig. 1 represents a top plan view of the condenser, the movable plates being shown in alinement with the stationary plates and in'the position of maximum capacity. Fig. 2 is a front view of the same. Fig. 3 is a side view of the same. Fig. 4 is a sectional view of the condenser with the supporting top plate removed, the

movable and stationary condenser plates be ing shown in the position of .minimum capacity.

Fig. 5 is a sectional view on an enlarged scale of the end of one of the posts upon which the stationary plates are mounted, and illustrating the insulating ball seated in said post and in an aperture of the adjacent supporting plate.

Referring now to the drawings in which like reference numerals denote corresponding parts throughout the several views, the frame of the condenser is made up of a pair of supporting plates 10 and H which are connected together by a plurality of rods 12,

13, 14, and -15. Between the supporting plates 10 and 11, the condenser is provided with a plurality of movable plates 16 secured upon a rotor shaft 17, and a plurality of stationary plates 17 arranged in spaced relation to said movable plates. The shaft 17 is'countersunk in its lower end forming a conical seat 18 for a pointed adjustable screw 19, the threads of which engage in a stationary nut 20 mounted in the bottom of .the supporting plate 11. The upper bearing for the shaft 17 comprises an annular gournal member 21 which is carried by the upper plate 10.

In order to secure the supporting frame to a radio set or other instrument, the-upper supporting plate 10 is provided with three upstanding rods 22, 23, and 23 The rods 22, 23, and 23 are adapted to engage against the panel of the radio set and may be tapped to receive suitable attaching screws passing through said panel. The upper extremity of the rotor shaft 17 is made sufiiciently long to extend I out throughNthe panel and is adapted to have a suitable tuning dial attached thereto, in any suitable manner, as F by a set screw.

Both sets of condenser plates 16 and 17 are made substantially semi-spherical in shape, and said stationary plates 17 have projections 24 and 25 at their opposite ends h for fitting into a pair of posts 26 and 27. The posts 26 and 27 are provided with coun tersunk recesses 28 at their opposite ends to provide circular line contacts with the inner sides of two pairs of insulating balls 29, as

most clearly shown in Fig. 5. The outer sides of said balls 29 are seated in apertures 30 formed in the upper and lower supporting plates 10 and 11, said apertures also engaging said balls along circular line con- 8 tacts.

By means of this construction, it will be evident that electrical leakage will be reduced to the minimum, and consequently the loss of signal strength which occurred in radio receiving sets employing the old type of condenser having surface contact in sulation will be avoided.

While there has been disclosed in this specification one form in which the invention may be embodied, it is to be understood that this form is shown for the purpose of illustration only, and that the invention is not to be limited to the specific disclosure but maybe modified and embodied in various other forms without departing from its spirit. lln short, the invention includes all the modifications and embodiments coming within the scope of the following claims.

Having thus fully described the invention, what is claimed as new, and for which it is desired to secure Letters Patent, is:

i. In a variable condenser, a pair of end supporting plates, means to connect said plates to form a rigid frame, a rotor shaft mounted in said supporting plates, a plurality of movable condenser plates secured ing therewith side edges of said hollow ends for holding menace said posts between said supporting plates. 2. In a variable condenser, a pair of end supporting plates, means to connect said plates to form a rigid frame, a rotor shaft nounted in said supporting plates, aplurality of movable condenser plates securedflt'o said shaft, a plurality of stationary condenser" plates interposed between and spaced from said movable plates, porting said stationary plates, and insulating balls between said su'pportingplates and the ends of said posts for holding'said posts in rigid position.

3. In a variablecondenser, a pair of end supporting plates, means to connect said plates to form a rigid frame, a rotor shaft mounted in said supporting plates, a plurality of movable condenser plates secured to said shaft, a plurality of stationary condenser plates interposed between and spaced from said movable plates, a pair of posts for supportingsaid stationary plates, and

insulating balls seated in the ends of said posts and in said supporting plates whereby the electrical leakage will be reduced.

4:. In a variable condenser, a pair of end supporting plates, means to connect said plates to form a rigid frame, a rotor shaft mounted in said supporting plates, a plu rality of movable condenser plates secured to said shaft, a denser plates interposed between and spaced from said movable plates, a pair of posts for supporting said stationary plates, said supportlng plates having apertures in alinement with said posts, and insulating balls seated in said apertures and in the ends of said osts, whereby electrical leakage will be re uced.

5. In a variable condenser, a pair of end supporting plates, means to connect said plates to form a rigid frame, a rotor shaft mounted in said supporting plates, a plu-- a pair of posts for sup denser p plurality of stationary conrality-of movable condenser to said shaft, a plurality of stationary condenser plates interposed between and spaced from said movable plates, posts for supporting said stationary plates, said supporting plates having apertures in alinementuwith said posts, the ends of said posts being countersunk, and insulating balls seated in said apertures and said countersunk ends, said balls engaging said apertures and said countersunk ends on line contacts plates secured only, whereby electrical leakage from said stationary plates will be reduced. 6. In a variable condenser, a supporting frame,'a' rotor shaft mounted in said frame nd carr ing a plurality of movable conates, and a plurality of stationary condenser plates spaced from and alternating with said movable plates, said stationary latesbeing su ported upon posts, said posts .at each end from said frame eingmsula'te by; insulating balls, and said balls having 1. line contacts with said frame and said posts,

whereby the I electrical leakage from said posts will be minimized. f '-:"7. In a variable condenser, a air of end supporting plates connected toget er to form a rigid frame, a rotor shaft, said rotor shaft having a countersunk hole in its bottom end,

means adjustably mounted in the bottom supporting plate ;for extending into said hole, means on the upper supporting plate to form another bearing for said shaft, a plurality of stationary plates interposed between'said movable plates, posts for supporting said stationary ,plates, and insulating balls separating said posts from said supporting plates for minimizing electrical leakage from said stationary plates.

8. In a variable condenser having alternately arranged movable and stationary contact plates, a supporting frame, a post for supporting said stationary plates, said post having a recess in its end, and-an insulated ball seated in said recess, said 'supportin frame having a seat for the outer side 0 signature to this sr ecification.

EARLE BARNES LEWIS.

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